 In 2005, he served in Iraq as a Judge Advocate General with the 155th Brigade Combat Team of Mississippi Army National Guard.Southwick also taught law as an adjunct professor at the Mississippi College School of Law and was a member of the American Inns of Court, Charles Clark Chapter.Southwick was nominated on January 9, 2007 by President George W. Bush to fill a seat on the Fifth Circuit vacated by recess-appointed Judge Charles W. Pickering, who retired at the end of 2004 because he could not overcome a filibuster launched against him by Senate Democrats.